JP5042597B2 - Method for manufacturing piezoelectric vibrating piece, piezoelectric vibrating piece and piezoelectric device - Google Patents

Description

  The present invention relates to a method for manufacturing a shape of a piezoelectric vibrating piece, and more specifically, a manufacturing method for manufacturing a piezoelectric vibrating piece having a clean cross-sectional shape by laser processing a wet-etched piezoelectric vibrating piece, and the manufacturing method. The present invention relates to a piezoelectric vibrating piece and a piezoelectric device.

  Conventionally, in consumer and industrial electronic devices such as watches, home appliances, various information / communication devices and OA devices, a piezoelectric vibrator, a piezoelectric vibrating piece and an IC chip are sealed in the same package as a clock source for the electronic circuit. Piezoelectric devices such as stopped oscillators and real-time clock modules are widely used. Piezoelectric vibratory gyros are widely used as rotational angular velocity sensors for attitude control and navigation control of ships, airplanes, automobiles, etc., and camera shake prevention / detection of video cameras, etc. Has been.

  In particular, these piezoelectric devices have recently been required to be further reduced in size and thickness as the electronic equipment on which they are mounted is reduced in size and thickness. In addition, there is a demand for a piezoelectric device that secures a low CI (crystal impedance) value and has high quality and excellent stability. In order to keep the CI value low, for example, a tuning fork type piezoelectric vibrating piece having a vibrating arm structure has been developed. As such a tuning fork type piezoelectric vibrating piece, for example, one described in Patent Document 1 is known.

  In this tuning fork type piezoelectric vibrating piece, for example, a wafer made of a piezoelectric single crystal material such as quartz is exposed by a photolithography technique, and then immersed in an etching solution for quartz. By performing this wet etching, the outer shape of the tuning-fork type piezoelectric vibrating piece is processed. Specifically, a corrosion resistant film is formed on both surfaces of a quartz wafer, and a photoresist is applied and dried thereon to form a resist film. Then, a photomask having the same shape pattern corresponding to the outer shape of the tuning-fork type piezoelectric vibrating piece is disposed on the resist film, and exposed and developed to expose the surface of the corrosion-resistant film. Then, the surface of the quartz wafer is exposed by removing the surface of the corrosion-resistant film with an etching solution.

Next, the exposed surface of the quartz wafer is etched with a quartz etching solution to process the outer shape of the vibrating piece including the vibrating arm. As the quartz wafer, for example, a quartz wafer cut out from the Z axis at a predetermined angle θ around the X axis is used. A tuning-fork type piezoelectric vibrating piece has a longitudinal direction, a width direction, and a thickness direction of a vibrating arm corresponding to a Y axis called a mechanical axis, an X axis called an electric axis, and a Z axis called an optical axis of a crystal structure of a crystal. Oriented. Therefore, the width direction of the vibrating arm coincides with the X-axis direction.
JP 2003-258331 A

  However, since the piezoelectric vibrating piece is formed of a piezoelectric single crystal material such as quartz having etching anisotropy, the wet-etched vibrating arm becomes asymmetric with respect to the center line due to its crystal orientation. In particular, the etching rate of crystal is dependent on the crystal axis and is easily etched in the width direction (+ X direction) of the vibrating arm. Therefore, the cross-section of the vibrating arm is not an ideal rectangle but an asymmetric cross-sectional shape.

  For this reason, the vibrating arm not only vibrates in the X direction during excitation, but also vibrates in the Z direction, generating a torsional moment and causing loss of strain energy. When the distortion energy loss of the piezoelectric vibrating piece increases, there is a problem that the natural frequency, that is, the oscillation frequency decreases, and the variation of the natural frequency increases. Further, in the above-described outer shape processing of the piezoelectric vibrating piece, there is a problem that it is difficult to form an electrode on the side surface portion of the vibrating arm.

  An object of the present invention is to provide a method for manufacturing a piezoelectric vibrating piece in which the cross section of the side surface of the piezoelectric vibrating piece has a clean rectangular shape. And the manufacturing method of the piezoelectric vibrating piece is to increase the productivity of the piezoelectric vibrating piece.

In order to achieve the above object, a manufacturing method for manufacturing a piezoelectric vibrating piece according to a first aspect of the present invention includes a step of preparing a flat plate piezoelectric material having etching anisotropy, and a piezoelectric vibrating piece on the piezoelectric material. In order to form the substrate, there are a step of wet etching the piezoelectric material and a laser processing step of irradiating the side surface of the wet-etched piezoelectric vibrating piece with laser light to remove a part of the side surface.
According to this configuration, when the outer shape of the piezoelectric vibrating piece is processed by wet etching from a piezoelectric material having etching anisotropy, the cross-sectional shape of the piezoelectric vibrating piece becomes asymmetric and a part of the side surface portion protrudes. However, by removing a part of the side surface portion with laser light, the asymmetry of the cross-sectional shape can be eliminated or improved. Therefore, loss of distortion energy due to vibration leakage can be prevented, and stable bending motion can be repeated. In addition, it is conceivable to process the outer shape of the piezoelectric vibrating reed directly with laser light without performing wet etching. However, this method takes a very long time. On the other hand, the manufacturing method for manufacturing the piezoelectric vibrating piece according to the first aspect has high productivity because only the side surface portion having an asymmetric cross section is processed with laser light.

According to the second aspect of the present invention, the piezoelectric vibrating piece is a tuning-fork type piezoelectric vibrating piece having at least two vibrating arms, and the laser processing step is performed on the side surfaces of the two vibrating arms. Laser processing.
According to such a configuration, the piezoelectric vibrating piece is a tuning fork-type piezoelectric vibrating piece having two vibrating arms. The tuning fork type piezoelectric vibrating piece vibrates only the vibrating arm and does not vibrate the base portion when excited. For this reason, by processing only the side surface portion of the vibrating arm with laser light, a vibrating arm that vibrates only in the width direction of the vibrating arm during excitation and does not vibrate in other directions can be obtained. The vibrating arm can prevent loss of distortion energy due to vibration leakage and stably repeat bending vibration. In addition, the productivity can be increased because the laser beam only needs to be processed on the side surface of the vibrating arm.

A manufacturing method for manufacturing a piezoelectric vibrating piece according to a third aspect of the present invention includes a step of forming a corrosion-resistant film on a piezoelectric material, a step of forming a resist film on the corrosion-resistant film, and a piezoelectric vibration on the resist film. And a step of exposing the shape of the piece. After this exposure step, a wet etching step is performed.
According to such a configuration, the corrosion-resistant film and the resist film are formed on at least one surface of the piezoelectric material. Laser light is irradiated to the piezoelectric material in this state. When removing a part of the side surface portion of the piezoelectric material, even if laser light is accidentally irradiated on one surface of the piezoelectric material, the laser light does not immediately reach the piezoelectric material because the corrosion-resistant film and the resist film exist. For this reason, the possibility that the piezoelectric vibrating piece becomes a defective product is reduced.

According to the fourth aspect of the present invention, in the laser processing step, the protective mask is disposed on the piezoelectric vibrating piece and then the laser beam is irradiated.
If the surface of the piezoelectric material is accidentally irradiated with laser light in a state where the corrosion resistant film and the resist film are removed from the surface of the piezoelectric material, the piezoelectric vibrating piece becomes a defective product. In order to prevent this, according to this configuration, a protective mask is not disposed immediately on the piezoelectric vibrating piece. Even when the corrosion-resistant film and the resist film are present on the surface of the piezoelectric material, if the protective mask is disposed, the piezoelectric vibrating piece can be reliably protected when the laser beam is accidentally irradiated.

According to the fifth aspect of the present invention, in the laser processing step, the laser beam is scanned within a predetermined range, and the stage on which the piezoelectric material is placed is moved outside the predetermined range. Irradiate the part with laser light.
With this configuration, since the laser beam is scanned within a predetermined range, the side surface of the piezoelectric vibrating piece can be irradiated with the laser beam at high speed and accurately. On the other hand, outside the predetermined range, the piezoelectric vibrating piece can be moved to a region where the laser beam can be irradiated by moving the stage.

In the manufacturing method for manufacturing the piezoelectric vibrating piece according to the sixth aspect of the present invention, the laser beam is a femtosecond laser.
The femtosecond laser is suitable for processing a piezoelectric vibrating piece having a size of several millimeters or less because it can realize precise processing without heat by a multiphoton absorption process.

In the manufacturing method for manufacturing the piezoelectric vibrating piece according to the seventh aspect of the present invention, the piezoelectric material includes a quartz substrate.
When the piezoelectric material is quartz and the piezoelectric vibrating piece is a tuning fork type, the longitudinal direction, the width direction, and the thickness direction of the vibrating arm are oriented corresponding to the Y-axis direction, the X-axis direction, and the Z-axis direction of the crystal, respectively. Since quartz has a high etching rate in the + X direction, the cross-sectional shape of the vibrating arm is asymmetric. For this reason, if a laser beam is irradiated to a side part and a part of side part is removed, the balance in the vibrating arm can be ensured favorable.

A manufacturing method for manufacturing a piezoelectric vibrating piece according to an eighth aspect of the present invention includes, in the seventh aspect, a substrate in which two quartz substrates whose etching anisotropies are opposite to each other are bonded to each other by siloxane bonding.
A piezoelectric vibrating piece for a gyro may be manufactured from a piezoelectric material in which two quartz substrates are combined. When such a bonded quartz substrate is wet etched, it is greatly affected by etching anisotropy. For such a bonded quartz substrate, a piezoelectric resonator element that exhibits stable vibration characteristics is manufactured by making the cross-section asymmetry in the width direction of the resonator element into a clean rectangular cross section by processing with laser light. be able to.

  According to another aspect of the present invention, a piezoelectric vibrating piece manufactured by the manufacturing method according to the above-described aspect or a further packaged piezoelectric device repeats a stable bending motion while preventing loss of strain energy due to vibration leakage. As a piezoelectric vibrating piece or a piezoelectric device, high quality is obtained.

According to the present invention, the step of forming a rectangular shape with a clean cross-sectional shape is performed by laser light after wet etching. Compared with laser processing without wet etching, the productivity is higher, the yield is higher, and the manufacturing can be performed at lower cost.
In addition, a part of the side surface that causes the asymmetry of the cross section due to the etching anisotropy of the piezoelectric vibrating piece can be removed to obtain a clean rectangular cross section. For this reason, since displacement in the thickness direction during excitation can be eliminated or suppressed, loss of strain energy due to vibration leakage can be prevented, and stable bending vibration can be secured. Therefore, the piezoelectric vibrating piece can realize very stable vibration characteristics in addition to high performance by suppressing the CI value.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration of piezoelectric vibration device>
FIG. 1A and FIG. 1B are diagrams of a piezoelectric vibration device 50 to which a manufacturing method as an embodiment of the etching method of the present invention is applied. 1A is a schematic plan view of the piezoelectric vibrating device 50 seen through, and FIG. 1B is a schematic cross-sectional view taken along line BB of FIG. 1A. In FIG. 1, the piezoelectric vibrating device 50 shows an example in which a tuning fork-shaped piezoelectric vibrating piece 20 is configured, and the piezoelectric vibrating device 50 accommodates the piezoelectric vibrating piece 20 in a package 51. The package 51 is formed, for example, by laminating and sintering a plurality of sheets formed by forming a ceramic green sheet made of an aluminum oxide-based kneaded material as an insulating material.

  In this embodiment, the package 51 includes a base substrate 51a, a wall substrate 51b, and a floor substrate 51c as shown in FIG. The package 51 is covered with a wall substrate 51b to form an internal space, and the piezoelectric vibrating piece 20 is accommodated in the internal space. A floor substrate 51c is disposed on the base substrate 51a so as to support the piezoelectric vibrating piece 20 at a predetermined height. The floor substrate 51c is provided with, for example, an electrode portion 52 formed by nickel plating and gold plating on tungsten metallization.

  The electrode portion 52 is connected to a mounting terminal 55 formed under the base substrate 51a. Accordingly, a driving voltage applied from the outside is transmitted to the electrode unit 52 via the mounting terminal 55 and finally supplied to the piezoelectric vibrating piece 20. Specifically, as shown in FIG. 1B, the mounting terminals 55 and the electrode portions 52 are routed around the outside of the package 51 by metallization, or using tungsten metallization or the like before firing the base substrate 51a. It can be formed by connecting with the formed conductive through hole (not shown). Here, in the present embodiment, the box-shaped package 51 is formed to accommodate the piezoelectric vibrating piece 20. For example, the piezoelectric vibrating piece is accommodated in a metal cylindrical case, and the piezoelectric vibrating piece 20 is accommodated. The lead connected to the resonator element may be hermetically sealed with a plug that leads to the outside.

  On the electrode part 52, a conductive adhesive 57 is applied, and the base part 29 of the piezoelectric vibrating piece 20 is joined. As the conductive adhesive 57, a synthetic resin agent serving as an adhesive component that exhibits bonding strength is added with a conductive filler (including conductive particles such as silver fine particles) and a predetermined solvent. Can be used.

  A lid 59 is joined to the open upper end of the wall substrate 51b by a sealing material 58 to be sealed. The lid 59 is preferably formed of a ceramic made of an aluminum oxide-based kneaded material. When formed of a metal material such as Kovar, the lid 59 is fixed to the wall substrate 51b by a technique such as seam welding.

  The piezoelectric vibrating piece 20 is made of, for example, quartz, and has a shape shown in FIG. 2 in order to obtain a small size and necessary performance. That is, the piezoelectric vibrating piece 20 includes a base portion 29 that adheres to the conductive adhesive 57 and a pair of vibrating arms that extend in parallel with the base portion 29 as a base end. That is, the piezoelectric vibrating piece 20 is a so-called tuning fork type piezoelectric vibrating piece that is entirely shaped like a tuning fork. In the present embodiment, the piezoelectric vibrating piece 20 including the pair of vibrating arms 21 will be described. However, the piezoelectric vibrating piece 20 including three or four vibrating arms 21 may be used.

  FIG. 2A is an enlarged perspective view of the piezoelectric vibrating piece 20. FIG. 2B is a BB cross-sectional view of FIG. In the piezoelectric vibrating piece 20, an extraction electrode 22 in which a gold (Au) layer is covered with a base chromium (Cr) layer is provided on a base 29 that is bonded to the conductive adhesive 57. Connected. The piezoelectric vibrating piece 20 includes a first crystal wafer 10a and a second crystal wafer 10b, and is coupled so that the electric axes 27 of the crystals are opposite to each other in the X-axis direction.

  A drive electrode 23, a monitor electrode 24, and a sense electrode 25 that are electrically connected to the extraction electrode 22 are formed on the surface of the pair of vibrating arms 21 that extend from the base portion 29. In FIG. 2B, “−” (minus) after drive electrode 23 and sense electrode 25 indicates a negative electrode, and “+” (plus) after drive electrode 23 and sense electrode 25. Indicates a positive electrode. The piezoelectric vibrating reed 20 is driven by a driver circuit (not shown) to start vibration and generates a monitor signal proportional to the magnitude of vibration from the monitor electrode 24, which is sent to the driver circuit via a monitor circuit (not shown). Provide feedback. In this way, the piezoelectric vibrating piece 20 is stably driven by a driving unit (not shown) that forms a closed loop.

<Structure of bonded crystal wafer>
FIG. 3 shows the bonded crystal wafer after the wet etching is completed.
FIG. 3A is a perspective view showing a configuration of a circular bonded crystal wafer 10 used in the present embodiment. The circular bonded crystal wafer 10 is made of, for example, an artificial crystal having a thickness of 0.8 mm, and the diameter of the circular bonded crystal wafer 10 is 3 inches or 4 inches. The circular bonded crystal wafer 10 includes a first crystal wafer 10a having a thickness of 0.4 mm and a second crystal wafer 10b having a thickness of 0.4 mm, both of which are Z-cut wafers cut in the Z-axis direction. ing. The first crystal wafer 10a and the second crystal wafer 10b are directly bonded, specifically, bonded by a siloxane bond (Si—O—Si) having excellent heat resistance. This siloxane bond is formed by bonding the surfaces of both the first crystal wafer 10a and the second crystal wafer 10b to a clean state, and then bonding the surfaces together, followed by annealing at about 500 ° C. . In order to bond the first crystal wafer 10a and the second crystal wafer 10b with siloxane, the first crystal wafer 10a and the second crystal wafer 10b are bonded so that their electric axes are opposite to each other in the X-axis direction. That is, the first crystal wafer 10a is bonded in the + (plus) X-axis direction and the second crystal wafer 10b is bonded in the-(minus) X-axis direction. Further, as shown in FIG. 3A, an orientation flat for specifying the crystal direction of the crystal is formed on a part of the peripheral portion 10e of the bonded crystal wafer 10 so that the axial direction of the circular bonded crystal wafer 10 can be specified. 10c is formed.

  FIG. 3B is a perspective view showing a configuration of a rectangular bonded crystal wafer 15 used in this embodiment. The rectangular bonded crystal wafer 15 is also made of, for example, an artificial crystal having a thickness of 0.8 mm, and one side of the rectangular bonded crystal wafer 15 is 2 inches. The rectangular bonded crystal wafer 15 also includes a first crystal wafer 15a having a thickness of 0.4 mm and a second crystal wafer 15b having a thickness of 0.4 mm, both of which are Z-cut wafers cut in the Z-axis direction. And bonded by a siloxane bond (Si—O—Si). In addition, in order to bond the first crystal wafer 15a and the second crystal wafer 15b with siloxane, the first crystal wafer 15a and the second crystal wafer 15b are bonded so that their electric axes are opposite to each other in the X-axis direction. An orientation flat 15c for specifying the crystal direction of the crystal is formed on a part of the peripheral edge portion 15e of the rectangular bonded crystal wafer 15 so that the axial direction of the rectangular bonded crystal wafer 15 can be specified.

  In the circular coupled quartz wafer 10 in FIG. 3A and the coupled quartz wafer 15 in FIG. 3B, a plurality of piezoelectric vibrating pieces 20 are formed by photolithography and wet etching. A plurality of window portions 18 are provided in relation to process management and wafer strength, and a plurality of piezoelectric vibrating reeds 20 are formed in the window portions. The orientation flat 10c or the orientation flat 15c of FIG. 3 and the position of each window 18 and the position of each tuning-fork type crystal vibrating piece 20 are defined. Therefore, the orientation flat 10c or the orientation flat 15c is also a positioning reference in laser processing described later. In the following embodiment, a circular bonded crystal wafer 10 having an orientation flat 10c shown in FIG.

<Cross section of piezoelectric vibrating piece after wet etching>
FIG. 4 shows one piezoelectric vibrating piece 20 of the bonded crystal wafer 10 after the wet etching shown in FIG. FIG. 4A is a perspective view of the piezoelectric vibrating piece 20 after wet etching. FIG. 4B is a cross section of the vibrating arm 21 viewed from the direction of the arrow shown in FIG. FIG. 4C is a cross-section of the vibrating arm 21 as viewed from the direction of the arrow shown in FIG. 4A as in FIG. 4B. It shows the state that has been done.

  Crystal has etching anisotropy with respect to the crystal etching solution. In particular, the etching rate of crystal is dependent on the crystal axis and is easily etched in the + X direction. For this reason, simply by performing wet etching, the side surface portion 211 has a sharp shape instead of the ideal rectangle shown in FIG. As shown in FIG. 4B or FIG. 4C, the trapezoidal shape in which the side surface portion 211 is line symmetric with respect to the siloxane bonding surface is stuck. For this reason, when the pair of vibrating arms 21 is excited, the bending of the vibrating arms 21 becomes unbalanced, and the vibration vibrates not only in the X direction but also in the Z direction. For this reason, the vibrating arm 21 receives a torsional moment in the thickness direction as a whole at the time of excitation, and bends and vibrates in the X direction while causing displacement in the Z direction. As a result, the vibration leaks and distortion energy is lost, or the vibration characteristics become unstable. This is processed by a laser processing device so that the cross section becomes a clean rectangular shape.

<Configuration of laser processing equipment>
FIG. 5 is a schematic diagram showing an apparatus configuration for removing (transpiration / sublimation) a part of the vibrating arm 21 of the piezoelectric vibrating piece 20 of the present invention, in particular, the side surface portion 211 using the laser beam LL. The piezoelectric vibrating piece 20 to which the crystal is removed is performed in a state where the piezoelectric vibrating piece 20 is connected to the coupled quartz wafer 10 as shown in FIG. This is because when the extraction electrode 22, the drive electrode 23, the monitor electrode 24, and the sense electrode 25 shown in FIG. 2 are formed after the laser processing, they are collectively processed by photolithography. However, when the electrodes are formed by placing them one by one on a pallet (not shown), the piezoelectric vibrating reeds 20 are cut out from the coupled crystal wafer 10 and the individual piezoelectric vibrating reeds 20 are laser processed. Good.

  The bonded crystal wafer 10 to which thousands of piezoelectric vibrating pieces 20 are connected is securely placed on the stage 124 by vacuum suction or mechanical clamp. The stage 124 is connected to a control circuit 111 that controls a motor 125 that moves the stage 124 in the XY directions. A laser drive circuit 120 that receives a signal from the control circuit 111 is connected to a femtosecond laser irradiation unit 122 using a titanium sapphire laser. The laser irradiation unit 122 irradiates the laser beam LL having a wavelength of 760 nm with a pulse of 10 KHz to 40 KHz. The XY drive circuit 130 that receives a signal from the control circuit 111 drives the X optical mirror 131 and the Y optical mirror 133 that are arranged in the optical path of the laser light LL. By moving the X optical mirror 131 in the X axis direction, the position in the X axis direction where the laser beam LL irradiates the piezoelectric vibrating piece 20 is changed. By moving the Y optical mirror 133 in the Y-axis direction, the position in the Y-axis direction where the laser beam LL irradiates the piezoelectric vibrating piece 20 changes.

  The X optical mirror 131 and the Y optical mirror 133 cannot make the optical path of the laser beam LL a distance greater than a threshold, for example, 10 mm. In this case, the control circuit 111 controls the motor 125 to move the stage 124. When the distance is shorter than the threshold value, the X optical mirror 131 and the Y optical mirror 133 change the optical path of the laser beam LL. The side part 211 to be removed from the piezoelectric vibrating piece 20 can be laser trimmed so as to scan with the laser beam LL. Since each of the piezoelectric vibrating reeds 20 can be scanned with the laser light LL at high speed without moving the stage 124, productivity can be improved.

  Since the femtosecond laser irradiation unit 122 is used, processing can be performed without accumulating heat at a minute portion from which the piezoelectric vibrating piece 20 is removed. Therefore, the piezoelectric vibrating piece 20 is damaged by the laser beam LL and its characteristics are changed. There is no end. Further, it is not necessary to perform laser trimming on the base 29 of the piezoelectric vibrating piece 20. If the vibrating arm 21 is flexibly vibrated only in the X direction so as not to receive a torsional moment during excitation, no loss of strain energy occurs. For this reason, laser trimming may be performed so that only the vibrating arm 21 has a rectangular shape.

It should be noted that the laser beam LL from the femtosecond laser irradiating unit 122 is protected so that the piezoelectric vibrating reed 20 is not defective due to being irradiated on the upper surface of the vibrating arm 21 and not the side surface 211 by mistake. The mask 135 may be arranged as necessary.
In addition to the femtosecond laser, a carbon dioxide laser or a green laser can be used.

<Process for forming outer shape of piezoelectric vibrating piece>
FIG. 6 is a flowchart for forming the outer shape of the piezoelectric vibrating piece 20.
In step S10, as described with reference to FIG. 3, the bonded crystal wafer 10 is prepared by bonding the first crystal wafer 10a and the second crystal wafer 10b.

  Next, in step S12, a corrosion resistant film is formed on the entire surface of the bonded crystal wafer 10 by a technique such as sputtering or vapor deposition. That is, when using a bonded crystal wafer 10 as a piezoelectric material, it is difficult to directly form gold (Au), silver (Ag), or the like, so chromium (Cr), titanium (Ti), or the like is used as a base. use. That is, in this embodiment, a metal film in which a gold layer is stacked on a chromium layer is used as the corrosion resistant film. For example, the chromium layer has a thickness of 500 angstroms and the gold layer has a thickness of about 1000 angstroms.

  In step S14, a photoresist layer is uniformly applied to the entire surface of the bonded crystal wafer 10 on which the chromium layer and the gold layer are formed by a technique such as spin coating. As the photoresist layer, for example, a positive photoresist made of novolak resin can be used.

  Next, in step S <b> 16, the external pattern of the piezoelectric vibrating piece 20 drawn on the photomask is exposed to the bonded crystal wafer 10 coated with the photoresist layer using an exposure apparatus. In step S16, both sides are exposed using i-line exposure light of 365 nm using a double-side exposure apparatus.

  In step S18, the photoresist layer of the bonded crystal wafer 10 is developed, and the exposed photoresist layer is removed. Further, the gold layer exposed from the photoresist layer is etched using, for example, an aqueous solution of iodine and potassium iodide. Next, the chromium layer exposed by removing the gold layer is etched with, for example, an aqueous solution of ceric ammonium nitrate and acetic acid. The concentration of the aqueous solution, the temperature, and the time of immersion in the aqueous solution are adjusted so that the excess portion is not eroded. Thus, the corrosion resistant film can be removed. Next, wet etching is performed on the quartz material exposed from the photoresist layer and the corrosion-resistant film so that the outer shape of the piezoelectric vibrating piece 20 is obtained using a hydrofluoric acid solution as a quartz etching solution. This wet etching takes about 6 hours to about 15 hours, although the time varies depending on the concentration, type and temperature of the hydrofluoric acid solution.

In step S20, the femtosecond laser beam LL is irradiated on the portion of the vibrating arm 21 of the piezoelectric vibrating piece 20 whose cross section is not rectangular due to etching anisotropy as described with reference to FIG. Then, the cross-sectional shape of the vibrating arm 21 is processed into a clean rectangle.
In step S22, the piezoelectric layer 20 having the vibrating arm 21 and the base 29 shown in FIG. 2 is formed by removing the photoresist layer and the corrosion-resistant film that are no longer needed. It is preferable not to remove the photoresist layer and the corrosion-resistant film before the laser processing in step S20. Even when the laser beam LL is accidentally irradiated on the upper surface of the vibrating arm 21 due to vibration around the processing apparatus, not on the side surface portion 211 of the vibrating arm 21 of the piezoelectric vibrating piece 20, there is a photoresist layer and a corrosion-resistant film. This is because the laser beam LL does not reach the quartz material and the piezoelectric vibrating reed 20 is less likely to be a defective product. That is, the photoresist layer and the anticorrosion film serve as the protective mask 135 shown in FIG.

  The preferred embodiments of the present invention have been described in detail above. However, as will be apparent to those skilled in the art, the present invention can be carried out with various modifications and changes made to the above embodiments within the technical scope thereof. . For example, in the tuning fork type piezoelectric vibrating piece of the present invention, various piezoelectric single crystal materials such as lithium niobate can be used in addition to quartz.

  In the present embodiment, the bonded crystal wafer 10 shown in FIG. 3 has been described, but a single crystal wafer that is not bonded may be used. FIG. 7 shows one piezoelectric vibrating piece 20 of a quartz single crystal wafer after wet etching. FIG. 7A is a perspective view of the piezoelectric vibrating piece 20 after wet etching a single crystal wafer. FIG. 7B is a cross section of the vibrating arm 21 viewed from the direction of the arrow shown in FIG. As described above, the crystal has etching anisotropy with respect to the crystal etching solution. Since quartz is easily etched in the + X direction, it is not the ideal rectangle shown in FIG. 2B, but a hexagonal shape or pentagon in which a part of the side surface protrudes in the + X direction as shown in FIG. 7B. It becomes a shape. Therefore, the present invention can also be applied to a single crystal wafer that is not bonded.

  Further, in addition to the piezoelectric vibrating piece 20 adhered in the same package as in FIG. 1, a piezoelectric device such as a gyro, a piezoelectric oscillator, or a real-time clock is configured by mounting an IC constituting its drive circuit and the like. be able to.

It is the figure of the piezoelectric vibration device 50 to which the manufacturing method as embodiment of the etching method of this invention is applied. (A) is the schematic plan view seen through of the piezoelectric vibration device 50, (b) is a schematic sectional drawing of the BB line of (a). FIG. 4A is an enlarged perspective view of the piezoelectric vibrating piece 20. (B) is BB sectional drawing of (a). It is the figure which showed the imaging crystal wafer of the state after wet etching was completed. (A) is a perspective view of a circular bonded crystal wafer 10, and (b) is a perspective view of a rectangular bonded crystal wafer 15. One piezoelectric vibrating piece 20 of the bonded crystal wafer 10 after wet etching. (A) is a perspective view of the piezoelectric vibrating piece 20 after wet etching, (b) is an example of the vibrating arm 21 as viewed from the arrow direction shown in (a), and (c) is also shown in (a). It is another example of the vibrating arm 21 seen from the arrow direction. It is the schematic which shows the apparatus structure which removes the side part 211 of the vibrating arm 21 using a laser beam LL (transpiration / sublimation). 4 is a flowchart for forming an outer shape of a piezoelectric vibrating piece 20. FIG. 4A is a perspective view of the piezoelectric vibrating piece 20 after wet etching a quartz single crystal wafer. (B) is the cross section of the vibrating arm 21 seen from the arrow direction shown to (a).

Explanation of symbols

10, 15 ... Bonded crystal wafer 20 ... Tuning fork type piezoelectric vibrating piece,
21 ...... Vibrating arm 211 ...... Side surface 23 ...... Drive electrode 24 ...... Monitor electrode 25 ...... Sense electrode 29 ...... Base 50 ...... Piezoelectric device 55 ...... Mounting terminal 57 ...... Adhesive 58 ...... Sealing material 59 ... Lid 111 ... Control circuit 120 ... Laser drive circuit 122 ... Femtosecond laser irradiation unit 130 ... XY drive circuit 131 ... X optical mirror 133 ... Y optical mirror 135 ... Protective mask LL ... Laser light

Claims (7)

In a manufacturing method for manufacturing a piezoelectric vibrating piece having a predetermined shape,
Preparing a flat piezoelectric material having etching anisotropy;
Wet-etching the piezoelectric material to form the piezoelectric vibrating piece in the piezoelectric material;
A laser processing step of irradiating the side surface portion of the wet-etched piezoelectric vibrating piece with laser light to remove a part of the side surface portion, and
The laser processing steps, without removing the photoresist layer and corrosion-resistant film used in the step of wet etching the piezoelectric resonator element, a manufacturing method of a piezoelectric vibrating piece and then irradiating the laser beam .   The piezoelectric vibrating piece is a tuning-fork type piezoelectric vibrating piece having at least two vibrating arms, and the laser processing step performs laser processing only on a side surface portion of the two vibrating arms. The method for manufacturing a piezoelectric vibrating piece according to claim 1, wherein: Forming a corrosion-resistant film on the piezoelectric material;
Forming a resist film on the corrosion-resistant film;
Exposing the shape of the piezoelectric vibrating piece to the resist film,
The method of manufacturing a piezoelectric vibrating piece according to claim 1 or 2, wherein the wet etching step is performed after the exposure step. The laser beam is transmitted through the first mirror that scans the laser beam in a first direction from a laser irradiation unit and the second mirror that operates the laser beam in a second direction that intersects the first direction. Irradiated to the side of the vibrating piece,
In the laser processing step, the laser beam is scanned within the scanning range of the first mirror and the second mirror, and the piezoelectric material is placed outside the scanning range of the first mirror and the second mirror. The method for manufacturing a piezoelectric vibrating piece according to claim 1, wherein the side surface portion of the piezoelectric vibrating piece is irradiated with laser light.   The method for manufacturing a piezoelectric vibrating piece according to claim 1, wherein the laser beam is a femtosecond laser.   The method for manufacturing a piezoelectric vibrating piece according to claim 1, wherein the piezoelectric material includes a quartz substrate. 7. The method of manufacturing a piezoelectric vibrating piece according to claim 6, wherein the quartz substrate includes a substrate in which two quartz substrates having opposite etching anisotropy are bonded with siloxane.